Mega Code Archive
A utility class for replacing properties in strings
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/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.util;
import java.util.Properties;
import java.io.File;
/**
* A utility class for replacing properties in strings.
*
* @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
* @author <a href="Scott.Stark@jboss.org">Scott Stark</a>
* @author <a href="claudio.vesco@previnet.it">Claudio Vesco</a>
* @author <a href="mailto:adrian@jboss.com">Adrian Brock</a>
* @author <a href="mailto:dimitris@jboss.org">Dimitris Andreadis</a>
* @version <tt>$Revision: 2898 $</tt>
*/
public final class StringPropertyReplacer
{
/** New line string constant */
public static final String NEWLINE = System.getProperty("line.separator", "\n");
/** File separator value */
private static final String FILE_SEPARATOR = File.separator;
/** Path separator value */
private static final String PATH_SEPARATOR = File.pathSeparator;
/** File separator alias */
private static final String FILE_SEPARATOR_ALIAS = "/";
/** Path separator alias */
private static final String PATH_SEPARATOR_ALIAS = ":";
// States used in property parsing
private static final int NORMAL = 0;
private static final int SEEN_DOLLAR = 1;
private static final int IN_BRACKET = 2;
/**
* Go through the input string and replace any occurance of ${p} with
* the System.getProperty(p) value. If there is no such property p defined,
* then the ${p} reference will remain unchanged.
*
* If the property reference is of the form ${p:v} and there is no such property p,
* then the default value v will be returned.
*
* If the property reference is of the form ${p1,p2} or ${p1,p2:v} then
* the primary and the secondary properties will be tried in turn, before
* returning either the unchanged input, or the default value.
*
* The property ${/} is replaced with System.getProperty("file.separator")
* value and the property ${:} is replaced with System.getProperty("path.separator").
*
* @param string - the string with possible ${} references
* @return the input string with all property references replaced if any.
* If there are no valid references the input string will be returned.
*/
public static String replaceProperties(final String string)
{
return replaceProperties(string, null);
}
/**
* Go through the input string and replace any occurance of ${p} with
* the props.getProperty(p) value. If there is no such property p defined,
* then the ${p} reference will remain unchanged.
*
* If the property reference is of the form ${p:v} and there is no such property p,
* then the default value v will be returned.
*
* If the property reference is of the form ${p1,p2} or ${p1,p2:v} then
* the primary and the secondary properties will be tried in turn, before
* returning either the unchanged input, or the default value.
*
* The property ${/} is replaced with System.getProperty("file.separator")
* value and the property ${:} is replaced with System.getProperty("path.separator").
*
* @param string - the string with possible ${} references
* @param props - the source for ${x} property ref values, null means use System.getProperty()
* @return the input string with all property references replaced if any.
* If there are no valid references the input string will be returned.
*/
public static String replaceProperties(final String string, final Properties props)
{
final char[] chars = string.toCharArray();
StringBuffer buffer = new StringBuffer();
boolean properties = false;
int state = NORMAL;
int start = 0;
for (int i = 0; i < chars.length; ++i)
{
char c = chars[i];
// Dollar sign outside brackets
if (c == '$' && state != IN_BRACKET)
state = SEEN_DOLLAR;
// Open bracket immediatley after dollar
else if (c == '{' && state == SEEN_DOLLAR)
{
buffer.append(string.substring(start, i - 1));
state = IN_BRACKET;
start = i - 1;
}
// No open bracket after dollar
else if (state == SEEN_DOLLAR)
state = NORMAL;
// Closed bracket after open bracket
else if (c == '}' && state == IN_BRACKET)
{
// No content
if (start + 2 == i)
{
buffer.append("${}"); // REVIEW: Correct?
}
else // Collect the system property
{
String value = null;
String key = string.substring(start + 2, i);
// check for alias
if (FILE_SEPARATOR_ALIAS.equals(key))
{
value = FILE_SEPARATOR;
}
else if (PATH_SEPARATOR_ALIAS.equals(key))
{
value = PATH_SEPARATOR;
}
else
{
// check from the properties
if (props != null)
value = props.getProperty(key);
else
value = System.getProperty(key);
if (value == null)
{
// Check for a default value ${key:default}
int colon = key.indexOf(':');
if (colon > 0)
{
String realKey = key.substring(0, colon);
if (props != null)
value = props.getProperty(realKey);
else
value = System.getProperty(realKey);
if (value == null)
{
// Check for a composite key, "key1,key2"
value = resolveCompositeKey(realKey, props);
// Not a composite key either, use the specified default
if (value == null)
value = key.substring(colon+1);
}
}
else
{
// No default, check for a composite key, "key1,key2"
value = resolveCompositeKey(key, props);
}
}
}
if (value != null)
{
properties = true;
buffer.append(value);
}
else
{
buffer.append("${");
buffer.append(key);
buffer.append('}');
}
}
start = i + 1;
state = NORMAL;
}
}
// No properties
if (properties == false)
return string;
// Collect the trailing characters
if (start != chars.length)
buffer.append(string.substring(start, chars.length));
// Done
return buffer.toString();
}
/**
* Try to resolve a "key" from the provided properties by
* checking if it is actually a "key1,key2", in which case
* try first "key1", then "key2". If all fails, return null.
*
* It also accepts "key1," and ",key2".
*
* @param key the key to resolve
* @param props the properties to use
* @return the resolved key or null
*/
private static String resolveCompositeKey(String key, Properties props)
{
String value = null;
// Look for the comma
int comma = key.indexOf(',');
if (comma > -1)
{
// If we have a first part, try resolve it
if (comma > 0)
{
// Check the first part
String key1 = key.substring(0, comma);
if (props != null)
value = props.getProperty(key1);
else
value = System.getProperty(key1);
}
// Check the second part, if there is one and first lookup failed
if (value == null && comma < key.length() - 1)
{
String key2 = key.substring(comma + 1);
if (props != null)
value = props.getProperty(key2);
else
value = System.getProperty(key2);
}
}
// Return whatever we've found or null
return value;
}
}
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